What makes a six-digit number easier to remember? I had the pleasure to be asked by Robbie Gonzalez, journalist at Wired, to help him solve that question.

Six-digit numbers are used for two-factor authentication. To illustrate: my bank asks me for a number whenever I want to make a transfer. It sends that number to my phone and I type it into my computer. The bank, having thus secured that the order is legitimate, allows me to make the transfer from my account.

Gonzalez had observed that some such numbers are user-friendlier than others. For instance, it is easier to remember 876 565 than 253 741. Why is that? Robbie […]